The Waal (Dutch name, pronounced [ʋaːl]) is the main distributary branch of the river Rhine flowing approximately 80 km (50 mi) through the Netherlands. It is the major waterway connecting the port of Rotterdam to Germany. Before it reaches Rotterdam, it joins with the Afgedamde Maas near Woudrichem to form the Boven Merwede. Along its length, Nijmegen, Tiel, Zaltbommel and Gorinchem are towns of importance with direct access to the river.

The river, which is the main channel in the Rhine–Meuse–Scheldt delta system, carries 65% of the total flow of the Rhine.

The name Waal, in Roman times called Vacalis, Vahalis or Valis, later Vahal, is of Germanic origin and is named after the many meanders in the river (West Germanic languages: wôh, lit. 'crooked'). It is, in turn, thought to have inspired early Dutch settlers of the Hudson Valley region in New York to name the Wallkill River after it (Waalkil "Waal Creek").

The current river shows little signs of these great bends, since it has been the subject of numerous normalisation projects carried out between the 18th and 20th centuries to improve the river as an economically important shipping route. Some of the cut-off bends are still visible near the main river and are sometimes reconnected to it in times of high water levels.

The Waal has significant adverse water quality due to discharge of raw sewage by France and Germany. A number of pathogens have been monitored to occur in the river waters from such sewage.^[9]